My haraella retrocalla likes to be in a closed "terrarium" with a mister that is on long enough to cause condensation. A few hours per day. I have a flower spike so I suppose my care is working out. I am always at the goodwill looking for cheap cool air room humidifiers.
See that little green spike?
Another way I have kept this is to fill a plastic shoe box with wet, wrung out spagham moss and then laid the stick it is mounted on upon the wet moss. A top would be better. I would keep it like this only for short periods of time.